Low temperature synthesis of semiconductor fibers

ABSTRACT

This invention presents a process to produce bulk quantities of nanowires of a variety of semiconductor materials. Large liquid gallium drops are used as sinks for the gas phase solute, generated in-situ facilitated by microwave plasma. To grow silicon nanowires for example, a silicon substrate covered with gallium droplets is exposed to a microwave plasma containing atomic hydrogen. A range of process parameters such as microwave power, pressure, inlet gas phase composition, were used to synthesize silicon nanowires as small as 4 nm (nanometers) in diameter and several micrometers long. As opposed to the present technology, the instant technique does not require creation of quantum sized liquid metal droplets to synthesize nanowires. In addition, it offers advantages such as lower growth temperature, better control over size and size distribution, better control over the composition and purity of the nanowires.

This application is a continuation in part of pending U.S.Nonprovisional application Ser. No. 09/896,834 filed on Jun. 29, 2001which claims priority from copending U.S. Provisional Application Ser.No. 60/214,963 filed on Jun. 29, 2000, and also claims priority frompending U.S. Provisional Application Ser. No. 60/302,062 filed on Jun.29, 2001, all of which are hereby incorporated by reference herein.

This application is part of a government project. The research leadingto this invention was supported by a Grant Number 9876251 from theNational Science Foundation. The United States Government retainscertain rights in this invention.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to the field of providing a synthesis technique togrow bulk quantities of semiconductor nanowires at temperatures lessthan 500° C.

2. Description of the Prior Art

One-dimensional semiconductor fibers are useful for many applicationsranging from probe microscopy tips to interconnections innanoelectronics. By “one-dimensional” it is meant that the fibers haveextremely small diameters, approaching 40 Ångstroms. The fibers may betermed “nanowires” or “nanowhiskers.” Several methods are known forsynthesis of these fibers. Included are VLS (vapor-liquid-solid) growthmechanism based laser ablation of silicon and silicon oxide species, andvariations of these techniques.

In VLS growth, a liquid metal cluster or catalyst acts as theenergetically favored site of absorption of gas-phase reactants. Thecluster supersaturates and the material grows in one dimension. VLSmechanism has been used to grow silicon nanowires by catalyticdecomposition of silane vapor on a gold metal surface. Variations ofthis mechanism have been used to produce other semiconductor fibers.

One variation is laser ablation. In this technique, the silicon oxidespecies, such as SiO₂, is ablated to the vapor phase by laserexcitation.

SUMMARY OF THE INVENTION

The present invention provides a method of synthesizing semiconductorfibers by placement of gallium or indium metal on a suitable substrate,placing the combination in a low pressure chamber at a vacuum from 100mTorr to one atmosphere in an atmosphere containing desired gaseousreactants, raising the temperature of the metal above its melting pointby microwave excitation, whereby the precursors form fibers of thedesired length. When the metal is gallium, a temperature of about atleast 50° C. is sufficient, preferably near 300° C. for best solubilityand mobility within the melt. When the metal is indium, a temperature ofabout 200° C is preferred. Preferably the substrate is silicon, mostpreferably silicon comprising an electronically useful pattern; themetal is gallium, the gaseous reactant is atomic hydrogen, and thefibers formed comprise of Si. The gallium metal may be applied either insolid or droplet form or in the form of patterned droplets forpatterning silicon nanowires. Gallium droplet patterns may includedroplets in two-dimensional and three-dimensional channels for directedgrowth.

Another preferable substrate is germanium with hydrogen as gaseousreactant. The reactant hydrogen will form germane, GeH_(x) in the gasphase which upon decomposition on gallium surface results in thedeposition of germanium into gallium droplets. The dissolved germaniumgrows out as germanium nanowires.

Other semiconductors materials may be synthesized according to themethods of this invention. In each case, gallium or indium metal is usedas the dissolution media. Where the solid substrate is not readilyetched to provide a gaseous precursor, a vapor source will be added tothe reactive atmosphere. For example, GaAs substrates may be used, witha gallium drop and nitrogen in the gas phase, to grow GaN nanofibers.

The present invention is for a process for synthesizing bulk amounts ofsemiconductor fibers by forming a low-melting and non-catalytic metal ona substrate, placing the combination in a low-pressure chamber, addinggaseous reactant, applying sufficient microwave energy to raise thetemperature in the chamber to a point above the melting point of themetal and continuing the process until fibers of the desired length areformed. The substrate selected can be silicon, the non-catalytic metalis gallium or indium, the gaseous reactant is atomic hydrogen, and thefibers comprise of silicon.

The instant invention also provides a process of synthesizing siliconfibers, the steps including forming a gallium layer about 100 micronsthick on a silicon substrate, placing the combination in a low-pressurechamber, reducing the pressure in the chamber to 50 Torr, addinghydrogen gas, applying sufficient microwave power to raise thetemperature in the chamber to 50° C. and continuing the process untilthe fibers are of the desired length.

These and other objects of the present invention will be more fullyunderstood from the following description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention will be had uponreference to the following description in conjunction with theaccompanying drawings in which like numerals refer to like partsthroughout the several views and wherein:

FIG. 1 shows a multitude of nanowires. These fibers were grown withH₂/N₂ ratio of 0.005, pressure of 30 Torr and microwave power of 1000 W;

FIG. 2 shows silicon nanofibers for short time scale growth (initial onehour);

FIGS. 3 shows a silicon nanoneedle after a growth experiment for 3hours. H₂/N₂ ratio was kept at 0.008. Chamber pressure was 40 Torr and800 W of microwave power was applied;

FIG. 4 shows a web of fibers grown for a longer time, five hours. Due tothe long growth duration, the grown wires were very long andintermingled;

FIG. 5 shows a multitude of oriented silicon fibers. These fibers weregrown with H₂/N₂ ratio of 0.0075, pressure of 50 Torr and 1000 W ofmicrowave power;

FIG. 6 is a schematic of the reaction chamber;

FIG. 7 shows silicon Nanowires grown using our Ga and plasma mediatedVLS process wherein the silicon nanowires (^(˜)10 nm size) growing as amultitude of filaments after a growth experiment for 8 hours with amicrowave power of 600 W, 30 torr pressure, and a total flow rate of 100sccm of hydrogen;

FIG. 8 shows silicon nanorods 150 nm thick, grown out of large galliumpool after a growth experiment for 5 hours with a microwave power of 900W, 50 torr pressure, and a total flow rate of ^(˜)100 sccm of hydrogenwith inlet H₂/N₂ ratio of 0.75;

FIG. 9 illustrates oriented growth of silicon nanowires ^(˜)100 nmthick, using pools of gallium melt employing experimental conditions ofa microwave power of 850 W. Pressure of 50 torr, growth duration of 5hrs, and inlet H₂/N₂ ratio of 0.75;

FIG. 10 shows bulk quantities of silicon nanowires produced after agrowth experiment for 5 hours with microwave power of 900 W, pressure of50 torr, and a total flow rate of 100 sccm of hydrogen;

FIG. 11 shows spaghetti like wires grown but of a different galliumdroplet on the same substrate as processed in FIG. 10;

FIG. 12 shows bulk quantities of very straight silicon nanowires grownusing the process of the present invention wherein the growth conditionsutilized 1000 W microwave power, 50 torr pressure, growth duration of 6hours, total gas flow rate of ^(˜)100 sccm with inlet H₂/N₂ ratio of0.75;

FIG. 13 shows a higher magnification SEM image of the wires grown out ofa different droplet on the same substrate as in FIG. 12;

FIG. 14 demonstrates nucleation of multiple sub-micron and nano-scale,silicon wires from a single gallium droplet wherein the growthconditions utilized 1000 W power, 30 torr, 3 hrs duration, and H₂/N₂:0.25;

FIG. 15 shows SEM image of multiple nanowires 50 nm thick growing out ofa single large gallium droplet wherein the growth conditions used 950 Wpower, 50 torr pressure, 7 hrs duration and H₂/N₂ of 0.95;

FIG. 16 shows a low magnification Transmission Electron Microscope imageof a web of silicon nanowires grown under the same conditions as thesample shown in FIG. 7;

FIG. 17 shows a typical Energy Dispersive Spectroscopy spectrum takenfrom an individual nanowires, confirming the nanowires to be composed ofsilicon with some surface native oxide;

FIG. 18 shows a high Resolution Transmission Electron Microscopy (HRTEM)image of a 4 nm thick silicon nanowires wherein the lattice spacingmatches that of bulk silicon;

FIG. 19 shows a high Resolution Transmission Electron Microscopy (HRTEM)image of a 4 nm thick silicon nanowires wherein the lattice spacingmatches that of bulk silicon;

FIG. 20 shows multiple gallium oxide rods growing out of a large galliumpool with growth conditions of 4 hour growth duration, 1000 W microwavepower, 30 Torr pressure, 100 sccm of hydrogen, 0.6 sccm of oxygen in theinlet stream;

FIG. 21 shows highly faceted gallium oxide fibers on the same sampleshown in FIG. 20;

FIG. 22 shows gallium oxide sub-micron thick fibers in addition to themicron-scale rods in the same sample mentioned above;

FIG. 23 shows a zoomed-out view of the quartz substrate wherein multiplefibers have been grown out of a large gallium pool;

FIG. 24 shows gallium oxide nanowires about 100 nm thick from adifferent region on the same sample as shown in FIG. 20;

FIG. 25 is another illustration of multiple nucleation and fiber growth;

FIG. 26 shows a scanning electron microscopy image of gallium oxideplatelets and crystals obtained in addition to the one-dimensionalstructures after a growth experiment under the same conditions as forsample in FIG. 20, whereby growth of gallium oxide can also be achievedwith a range of abovementioned process parameters and with differentsubstrate materials;

FIG. 27 shows a scanning electron microscopy image of gallium oxideplatelets and crystals obtained in addition to the one-dimensionalstructures after a growth experiment under the same conditions as forsample in FIG. 20, whereby growth of gallium oxide can also be achievedwith a range of abovementioned process parameters and with differentsubstrate materials;

FIG. 28 shows a scanning electron microscopy image of gallium oxideplatelets and crystals obtained in addition to the one-dimensionalstructures after a growth experiment under the same conditions as forsample in FIG. 20, whereby growth of gallium oxide can also be achievedwith a range of abovementioned process parameters and with differentsubstrate materials;

FIG. 29 shows a scanning electron microscopy image of: gallium oxideplatelets and crystals obtained in addition to the one-dimensionalstructures after a growth experiment under the same conditions as forsample in FIG. 20, whereby growth of gallium oxide can also be achievedwith a range of abovementioned process parameters and with differentsubstrate materials;

FIG. 30 shows a micrograph of carbon nanofibers of various thickness andlength wherein the growth Conditions utilized a microwave power of 700W, pressure of 40 torr, 4 hr duration, 100 sccm of hydrogen and 2 sccmof methane in the plasma; however these process parameters can be variedand synthesis of carbon nanowires obtained;

FIG. 31 shows a micrograph of carbon nanofibers of various thickness andlength wherein the growth Conditions utilized a microwave power of 700W, pressure of 40 torr, 4 hr duration, 100 sccm of hydrogen and 2 sccmof methane in the plasma; however these process parameters can be variedand synthesis of carbon nanowires obtained;

FIG. 32 shows a micrograph of carbon nanofibers of various thickness andlength wherein the growth Conditions utilized a microwave power of 700W, pressure of 40 torr, 4 hr duration, 100 sccm of hydrogen and 2 sccmof methane in the plasma; however these process parameters can be variedand synthesis of carbon nanowires obtained; and

FIG. 33 shows a microaraph of carbon nanofibers of various thickness andlength wherein the growth Conditions utilized a microwave power of 700W, pressure of 40 torr, 4 hr duration, 100 sccm of hydrogen and 2 sccmof methane in the plasma; however these process parameters can be variedand synthesis of carbon nanowires obtained.

DESCRIPTION OF THE PREFERRED EMBODIMENT

This invention provides a novel synthesis route for growingone-dimensional structures of semiconductor materials in wire, whiskerand rod shapes at temperatures well under 550° C., preferably less than300° C. This low-temperature synthesis is made possible by the use ofgallium as a preferable absorption site. Gallium has a low meltingtemperature (^(˜)30° C.) and broad temperature range for the melt phase(30-2400° C. at 1 atm). Indium, which has a melting temperature of156.6° C., and a melt range of 156.6 to 2000° C., is also useful as adissolution medium. In one embodiment of the invention of the invention,growth of silicon fibers was observed when silicon substrates coveredwith a thin film of gallium were exposed to mixture of nitrogen andhydrogen in a microwave-generated plasma. The resulting silicon wiresranged from several microns to less than ten (10) nanometers indiameter. The observed growth rates were on the order of 100microns/hour. Results indicate that this technique is capable ofproducing oriented rods and whiskers with narrow diameter distributions.The growth mechanism in this method is hypothesized to be similar tothat in other VLS process, i.e., rapid dissolution of silicon solute ingallium melt, formation of nuclei, nuclei surfacing out of the galliummelt, growth of silicon in one dimension in the form of fibers.

This technique offers several advantages over conventional VLStechniques using silicon-transition metal eutectic for catalyzed growth.When the desired fibers comprise silicon or germanium, there is no needto supply silicon or germanium in solid form. Secondly, the very lowtemperatures required when using gallium as the dissolution mediumallows easier integration with other processing techniques and materialsinvolved in electronics and opt-electronic device fabrication. Nanometerscale one-dimensional semiconductor structure such as nanowires andnonwhiskers are expected to be critically important in advancedmesoscopic electronic and optical device applications.

The advantage of low-temperature fabrication are also useful for thosesemiconductors in which the substrate and the fibers differ incomposition. In such case, both or all fibers components may be providedin the vapor phase.

To more explicitly teach the methods of this invention, the followingdetailed embodiments are provided for purposes of illustration only.Those skilled in the art may readily make substitutions and variationsin substrates and reactants to synthesize other semiconductors on agallium catalyst. Such substitutions and variations are considered to bewithin the spirit and scope of this invention. The following examplesdescribe preferred embodiments of the invention. It is intended that thespecification, together with the examples, be considered exemplary only,with the scope and spirit of the invention being indicated by the claimswhich follow the examples.

EXAMPLE 1 Bulk Synthesis of Silicon Fibers

A silicon substrate (2 cm×2 cm) was prepared by cleaning with a 45% HFsolution, thoroughly rinsing in acetone and ultra-sonication. Dropletsof gallium metal at 70° C. were applied to form a film with a thicknessof approximately 100 microns. The nitrogen flow rate was set to 100sccm. The pressure in the reactor was set to 30 Torr. Microwaves at 2.45Ghz were used to ionize the nitrogen gas. The input microwave power was1000 W. The experiments were done in an ASTeX model 5010 bell jarreactor chamber equipped with an ASTeX model 2115 1500 W microwave powergenerator. 0.5 sccm of hydrogen were introduced into the nitrogenplasma. The reaction was carried out for six hours. Graphite blocks wereused as substrate stage. The quartz bell jar volume was approximately2000 cc. FIG. 6 shows a schematic of the reactor. After the growthexperiments, the silicon substrate covered with an ashy mass wasobserved under a scanning electron microscope (SEM). FIGS. 1 through 16show micrographs of silicon fibers of various thickness and length. FIG.1 shows a group of nanowires. These fibers were grown with H₂/N₂ ratioof 0.005, pressure of 30 Torr and microwave power of 1000 W. FIG. 2shows silicon nanofibers for short time scale growth (initial one hour).FIG. 3 shows a silicon nanoneedle. H₂/N₂ ratio was kept at 0.008.Chamber pressure was 40 Torr and 800 W of microwave power was applied.FIG. 4 shows a web of fibers grown for a longer time, five hours. Due tothe long growth duration, the grown wires were very long andintermingled. The limitation on wire length is time-dependant, but notprocess-dependant FIG. 5 shows a multitude of oriented silicon fibers.These fibers were grown with H₂/N₂ ratio of 0.0075, pressure of 50 Torrand 1000 W of microwave power. FIG. 7 shows silicon Nanowires grownusing the instant Ga and plasma mediated VLS process. Silicon nanowires(^(˜)10 nm size) growing as a multitude of filaments after a growthexperiment for 8 hours with a microwave power of 600 W, 30 torrpressure, and a total flow rate of 100 sccm of hydrogen. The micrographwas taken using a Hitachi S900 Field Emission Scanning ElectronMicroscope at an acceleration voltage of 2 kV and a magnification of ×60K. FIG. 8 shows oriented silicon nanorods 150 nm thick, grown out oflarge gallium pool after a growth experiment for 5 hours with amicrowave power of 900 W, 50 torr pressure, and a total flow rate of^(˜)100 sccm of hydrogen with inlet H₂/N₂ ratio of 0.0075. FIG. 9illustrates oriented growth of silicon nanowires ^(˜)100 nm thick, usinglarge pools of gallium melt. These nanowires were grown for 5 hours withmicrowave power of 850 W, Pressure of 50 torr, and inlet H₂/N₂ ratio of0.0075. FIG. 10 shows profuse quantities of silicon nanowires producedafter a growth experiment for 5 hours with microwave power of 900 W,pressure of 50 torr, and a total flow rate of 100 sccm of hydrogen. Thenanowires were imaged using a Hitachi 3200N scanning electron microscopeat an acceleration voltage of 20 kV and a magnification of ×7 k. FIG. 11shows spaghetti like wires grown out of a different gallium droplet onthe same sample as in FIG. 10. FIG. 12 shows bulk quantities of verystraight silicon nanofilaments grown for 6 hours with 1000 W microwavepower, 50 torr pressure, and a total gas flow rate of 100 sccm withinlet H₂/N₂ ratio of 0.0075. FIG. 13 shows a higher magnification SEMimage of the wires grown out of a different droplet on the samesubstrate as in FIG. 12. FIG. 14 demonstrates the fact that multiplenanowires can nucleate and grow out of a large gallium pool in ourtechnique, unlike in traditional VLS techniques, where one has to createnanometer sized catalyst particles. Multiple sub-micron and nano-scalesilicon wires are shown to grow out of a single large gallium droplet.These fibers were grown for 3 hours with 1000 W microwave power, 30torr, and H₂/N₂ ratio of 0.0025. FIG. 15 shows SEM image of multiplenanowires 50 nm thick growing out of a single large gallium droplet.These fibers were grown for 7 hours with a microwave power of 950 W,pressure of 50 torr and H₂/N₂ ratio of 0.0095. FIG. 16 shows a web ofsilicon nanowires grown under the same conditions as the sample shown inFIG. 7. These nanowires imaged using a JEOL 2000FX Transmission ElectronMicroscope at an acceleration voltage of 200 kV and a magnification of×300 k. The elemental composition of the fibrous structures wasdetermined using Energy Dispersive Spectroscopy (EDX), a feature in theJEOL 2000FX microscope. FIG. 17 shows a representative EDX spectrum ofan individual nanowires shown in FIG. 16. The nanowires composed ofsilicon, with some surface oxidation. The copper peak appeared due tothe copper grid material. FIG. 18 and 19 represent-high resolutionTransmission Electron Microscopy images of two different siliconnanowires about 4 nm thick. The fringes in these micrographs representlattice planes in the nanowires. The lattice spacing was measured usingthe Digital Micrograph software, which matched the values for bulksilicon lattice spacings.

EXAMPLE 2 Bulk Synthesis of Gallium Oxide Fibers

Gallium oxide fibers can be grown using the above plasma mediatedtechnique. A quartz substrate (2 cm×2 cm) was prepared byultra-sonication in IsoPropyl Alcohol. Droplets of gallium metal at 70°C. were applied to form a film with a thickness of approximately 100microns. The hydrogen flow rate was set to 100 sccm. The pressure in thereactor was set to 40 Torr. Microwaves at 2.45 Ghz were used to ionizethe hydrogen gas. The input microwave power was 700 W. The experimentswere done in an ASTeX model 5010 bell jar reactor chamber equipped withan ASTeX model 2115 1500 W microwave power generator. 0.6 sccm of oxygenwere introduced into the hydrogen plasma. The reaction was carried outfor four hours. Graphite blocks were used as substrate stage. After thegrowth experiments, the quartz substrate covered with a whitish mass wasobserved using a scanning electron microscope (SEM). FIGS. 20 through 25show micrographs of gallium oxide fibers of various thickness andlength. FIG. 20 shows multiple gallium oxide rods growing out of a largegallium pool. The fibers are very well faceted and were grown for 4hours with 1000 W microwave power, 30 Torr pressure, 100 sccm ofhydrogen, and 0.6 sccm of oxygen in the inlet stream. FIG. 21 showshighly faceted gallium oxide fibers on the same sample shown in FIG. 20.The micrographs were taken using a LEO 1430 Scanning Electron Microscopeat an acceleration voltage of 20 kV. FIG. 22 shows gallium oxidesub-micron thick fibers in addition to the micron-scale rods in the samesample mentioned above. FIG. 23 shows an overall zoomed out view of thequartz substrate, demonstrating the fact that multiple fibers cannucleate and grow out of a large gallium pool using our technique. FIG.24 shows gallium oxide nanowires about 100 nm thick from a differentregion on the same sample as shown in FIG. 20. FIG. 25 is anotherillustration of multiple nucleation and fiber growth. In addition to theone-dimensional structures, we also observed gallium oxide plateletsabout 100-200 nm thick, as shown in FIG. 26 through 29. Gallium oxidefibers were also synthesized with gallium droplets spread on othersubstrates, such as pyrolytic boron nitride, alumina, and glassy carbon.In addition to different fractions of O₂/H₂ being used, fractions ofmethane and nitrogen were also introduced into the plasma and synthesisof gallium oxide fibers was obtained.

EXAMPLE 3 Synthesis of Carbon Nanofibers

Carbon nanofibers have been grown using the above plasma-mediatedtechnique. A pyrolytic boron nitride substrate (^(˜)1 cm×1 cm) wasprepared by ultra-sonication in IsoPropyl Alcohol. The substrate wascovered with molten gallium droplets. The hydrogen flow rate was set to100 sccm. The pressure in the reactor was set to 40 Torr. Microwaves at2.45 Ghz were used to ionize the hydrogen gas. The input microwave powerwas 700 W. The experiments were done in an ASTeX model 5010 bell jarreactor chamber equipped with an ASTeX model 2115 1500 W microwave powergenerator. 2.0 sccm of methane were introduced into the hydrogen plasma.The reaction was carried out for four hours. Graphite blocks were usedas substrate stage. After the growth experiments, the quartz substratecovered with a grey mass was observed using a scanning electronmicroscope (SEM). FIGS. 30 through 33 show micrographs of carbonnanofibers of various thickness and length. FIG. 30 shows multiplecarbon filaments growing out of a large gallium droplet. The fibers FIG.31 shows a higher magnification image of approximately 50 nm thicknanofilaments.

EXAMPLE 4 Synthesis of Germanium Fibers

Germanium fibers can be grown using the above technique by using eithergermanium substrate or using germane in the vapor phase. The gas phasewill preferably consist of hydrogen with or without nitrogen to resultin the formation of germane radicals, a gaseous source of germanium.Germane will be decomposed on the gallium substrate resulting indissolution of germanium into the gallium melt.

EXAMPLE 5 Synthesis of Gallium Nitride Fibers

Nitrogen can also be dissolved into gallium melt, but at relativelyhigher temperatures than above, i.e., above ^(˜)600° C. At thesetemperatures, using gallium droplets exposed to an atomic nitrogensource, such as plasma, one can achieve nitrogen saturated galliummelts. These nitrogen saturated gallium melts will form gallium nitrideeither in the whisker or nanowire form.

EXAMPLE 6 Synthesis of Silicon Nitride Fibers and Whiskers

Using a similar setup as that used for example 1, one can expose thegallium droplet to nitrogen and hydrogen plasma at relatively highertemperature, i.e., ^(˜)600° C., to achieve the dissolution of bothnitrogen and silicon into the gallium droplet.

The foregoing detailed description is given primarily for clearness ofunderstanding and no unnecessary limitations are to be understoodtherefrom, for modification will become obvious to those skilled in theart upon reading this disclosure and may be made upon departing from thespirit of the invention and scope of the appended claims. Accordingly,this invention is not intended to be limited by the specificexemplifications presented hereinabove. Rather, what is intended to becovered is within the spirit and scope of the appended claims.

1. (canceled)
 2. (canceled)
 3. (canceled)
 4. (canceled)
 5. A process forsynthesizing bulk amounts of semiconductor nanofibers, the stepscomprising: forming a film of a low-melting metal on a substrate;placing said film in a low-pressure chamber; adding a gaseous reactant;applying energy to raise the temperature in said low-pressure chamber toa point above the melting point of said low-melting metal forming amolten metal film; activating and decomposing a gas phase yieldinggrowth precursors and exposing said molten metal film to said activatedgas phase; and continuing the process forming multiple nanofibers of thedesired length.
 6. The process of claim 5, wherein said substrate is asilicon.
 7. The process of claim 5, wherein the low-melting metalcomprises gallium.
 8. The process of claim 5, wherein said gaseousreactant comprises atomic hydrogen.
 9. The process of claim 5, whereinsaid nanofibers comprise silicon.
 10. The process of claim 5, whereinsaid low-melting metal comprises indium.
 11. The process of claim 5,wherein said substrate is selected from the group consisting of silicon,quartz, pyrolytic boron nitride, alumina, glassy carbon, germanium,graphite, and gallium.
 12. The process of claim 5, wherein saidsubstrate comprises an electronically useful pattern.
 13. The process ofclaim 5, wherein said gaseous reactant comprises nitrogen.
 14. Theprocess of claim 5, wherein said gaseous reactant comprises hydrogen andnitrogen.
 15. The process of claim 5, wherein said low melting metalcomprises gallium oxide.
 16. The process of claim 5, wherein saidgaseous reactant comprises germane.
 17. The process of claim 5, whereinsaid nanofibers comprises germanium.
 18. The process of claim 5 whereinsaid gaseous reactant comprises hydrogen and germane and said substratecomprises gallium decomposing to yield a germanium and a galliumprecursor simultaneously and nanofibers comprising a germanium galliumalloy.
 19. The process of claim 5 wherein said gaseous reactantcomprises nitrogen and said substrate comprises gallium decomposing toyield a nitrogen and a gallium precursor simultaneously and nanofiberscomprising a gallium nitride alloy.
 20. The process of claim 5 whereinsaid gaseous reactant comprises hydrogen and nitrogen and said substratecomprises silicon decomposing to yield a nitrogen and a siliconprecursor simultaneously and nanofibers comprising a silicon nitridealloy.
 21. The process of claim 5, wherein said gaseous reactantcomprises hydrogen and germane and said substrate comprises silicondecomposing to yield a germanium and a silicon precursor simultaneouslyand nanofibers comprising germanium silicon alloy.
 22. The process ofclaim 5, wherein the pressure in the low-pressure chamber ranges frombetween 30 Torr to 760 Torr.
 23. The process of claim 5, wherein saidfilm of a low-melting metal comprises the shape of a droplet.
 24. Theprocess of claim 5, wherein said film of a low-melting metal is about100 microns in thickness.
 25. The process of claim 5, wherein saidnanofibers are from 4 nanometers to several microns in diameter.
 26. Theprocess of claim 5, wherein said nanofibers are several micrometers inlength.